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H. Sun, M.W. Dul, W.H. Swanson; Comparison of Conventional, FDT and Gabor–Based Perimetry in the Macula . Invest. Ophthalmol. Vis. Sci. 2005;46(13):3720.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: In the central ±30° of visual field, comparable depth of glaucomatous defects has been reported for conventional perimetry with a size III circular stimulus and for CRT–based perimetry with sinusoidal patterns (Harwerth et al., American Academy of Optometry, 2003; Pan et al., ARVO 2003, No. 56). This result may not extend to the macula due to the higher spatial tuning in the fovea. The purpose of the current study was to compare conventional and CRT–based macular perimetry for patients with glaucoma. Methods: Twenty–two patients with glaucoma were evaluated with four perimetry tests: a conventional SITA 10–2 with Goldmann size III circular stimuli (0.43° in diameter) using a Humphrey Field Analyzer, two frequency–doubling tests (10–2 FDT, Macula FDT) with grating stimuli (0.5 cpd, 2°x2° square) using a Humphrey Matrix, and a test with Gabor stimuli (0.5 cpd, 6° in diameter) using a customized VSG–controlled CRT system. All tests were performed with the same eye in a single visit, and test order was counter–balanced. To compare results on conventional and CRT–based perimetry tests, we converted the thresholds for the SITA 10–2 into Weber contrast, and results from all four tests were expressed as log contrast sensitivity in decibel (dB) units (10 dB per log unit). To evaluate the effect of defect depth on sensitivity for 10–2 FDT and SITA 10–2, the difference between the two sensitivities was plotted versus their mean, and the means were grouped into twelve 2–dB bins (ranged from –10 to +14 dB). Similar analysis was also performed for 10–2 FDT and the Gabor–based tests. Results: Contrast sensitivity for the FDT stimuli was higher than for the SITA 10–2 stimuli by an average of 8.2 ± 4.9 dB. Sensitivity differences between FDT and SITA 10–2 for different bins averaged from 7.1 to 9.0 dB with SDs ranging from 1.5 to 6.3 dB. The exception was the 3% of points with the lowest SITA 10–2 sensitivities, where the sensitivity difference averaged 27.5 ± 6.9 dB. FDT sensitivity averaged 4.6 ± 1.8 dB higher than Gabor sensitivity, with little dependence on the mean sensitivity (r2<0.001, p>0.90). For 69% of the locations where thresholds could not be obtained with the SITA 10–2 test, contrast sensitivity could still be measured with FDT and Gabor tests. Conclusions: Depth of defect was similar for all three stimuli except at locations of the lowest SITA 10–2 sensitivity, where performance was better for sinusoidal stimuli. FDT and Gabor tests gave similar results despite their different temporal profiles. The results are consistent with the predictions of the cortical pooling model of glaucoma (Swanson et al., 2004; IOVS 45:466–472).
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